One form of method of dynamically balancing a rotary member, such as a motor vehicle wheel, by mass correction in two correction or balancing planes on the rotary member involves carrying out calibration runs for ascertaining transformation characteristics of a measuring assembly in which measurement value vectors are ascertained as the effects of unbalance of the rotary member in measuring planes of the measuring assembly. Those characteristics of the measuring assembly are then stored. In dependence on the stored characteristics, correction or balancing vectors are then ascertained from the measurement value vectors, in a plane-computing means, for mass correction or balancing which is to be effected in the two correction planes of the rotary member.
However the system which consists of the rotary member to be balanced and its mounting in the measuring assembly is a spring-mass-damper system which is excited at the measurement speed of rotation of the rotary member by the centrifugal force caused by unbalance of the rotary member. Bearing anisotropy phenomena and other mechanical and electrical aspects of the measuring assembly also have an effect on the measurement results produced. That gives rise to phase shifts as between the measured and the actual unbalances of the rotary member. That aspect becomes clearly apparent in the plane separation operation which indicates the influence of an unbalance existing in the one correction plane, on the display of unbalance provided by the measuring assembly with respect to the other correction plane. The ideal in that respect would be a display 0 in the other plane.